


Needs Must

by Tarash



Category: Supergirl (TV 2015)
Genre: Alien Cock, Aphrodisiacs, Fuck Or Die, Kink Meme, M/M, Mating Cycles/In Heat, Mildly Dubious Consent, Plot What Plot/Porn Without Plot, Xeno
Language: English
Status: Completed
Published: 2016-12-26
Updated: 2016-12-26
Packaged: 2018-09-12 12:12:02
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 6,870
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9071086
Author URL: https://archiveofourown.org/users/Tarash/pseuds/Tarash
Summary: J'onn J'onzz is going through a heatcycle, and Mon-El has not only figured out what's going; he's decided he's going to help J'onn through it.





	

**Author's Note:**

> From the following prompt at the DCTV kinkmeme: http://dctv-kinkmeme.dreamwidth.org
> 
> "J'onn has a mating cycle, gets hit by sex pollen that only affects him, and HAS to have sex or he'll die. Bonus if in his true form, bonus if he doesn't have human dick."
> 
> The mildly dubious consent in the tags comes from the aphrodisiac secretions in Green Martian come that affect Mon-El.

“Is J’onn all right?” Mon-el asks Alex, in a rare quiet moment at the DEO.  
  
Alex frowns at him. “Why do you ask?”  
  
Mon-el shrugs. “He seems...quieter than usual.” And tenser. And more withdrawn. As if his attention isn’t fully on the task at hand, which isn’t like J’onn, although Mon-el hasn’t known him as long as Alex has. “And he spends more time in his quarters.”   
  
“It might be a side-effect from the whole White Martian thing,” Alex muses, “or it might just be J’onn being J’onn.” She gives Mon-el a smile. “Or maybe he’s not used to sharing the DEO with someone else after hours, and he’s decided he needs some privacy.”  
  
It’s a logical answer. For the first few weeks that Mon-el lived at the DEO, J’onn taught him some basic facts about Earth, and humans, and the culture of the United States. The lessons were pretty dry, but useful, and Mon-el kind of misses J’onn lecturing him on historical events.   
  
But Alex has a point. J’onn is a very private man, and it makes sense that he doesn’t want to spend every evening teaching Mon-el about humans.   
  
“You’re probably right,” Mon-el replies, and smiles back. “Thanks.”   
  
He’s still gonna keep an eye on J’onn, though, just in case it _is_ side-effects from the medicine to reverse the effects of the White Martian blood on him.

*

Mon-El watches closely, but keeps his distance from J’onn so he doesn’t arouse the other man’s suspicion or disturb his possible need for privacy.   
  
But as the week goes by, Mon-El notices more things that seem wrong. J’onn is sweating more, for one, and is definitely more easily distracted and closed off. He avoids touching other people - more than usual.   
  
Mon-El only notices that symptom one afternoon when Winn, having discovered an essential clue that’ll help them track down a hostile alien, wants to high-five Alex and J’onn.   
  
Alex rolls her eyes and high-fives Winn, but J’onn lets his arms hang down by his side and ignores Winn, until Winn sighs, grabs J’onn’s wrist and raises his arm to high-five him. “C’mon, J’onn, a little bit of team spirit!” Winn says, when J’onn immediately pulls his wrist away.   
  
J’onn glowers at Winn, and stalks away. Alex and Winn exchange a worried look. “He’s probably just worried over who the alien is gonna go after next,” Alex says, patting Winn on the arm. “You know what he’s like.” She gives Winn a quick smile, then follows J’onn.   
  
Mon-El saunters over to Winn. “That was weird,” he says.   
  
Winn turns his head away from the direction Alex went, and to Mon-El. “A little? I mean, it’s J’onn.”   
  
“Still weird. Is that the first time he did that?”   
  
Winn shrugs. “He usually glares at me then holds up his hand and lets me do all the work.” He leans back in his chair. “I don’t know, man, but I gotta get back to this. Make sure we keep an eye on this parasite-thing.”   
  
For the rest of the day, Mon-El stays out of the way and just observes. J’onn definitely avoids all physical contact, from accidental brushes to a friendly pat on the back. And since J’onn isn’t a physical guy, it’s barely noticeable, so Mon-El decides to test it.   
  
That evening, he walks into J’onn’s private quarters after knocking on the door. “Evening!” he announces cheerfully, holding a book on South America he borrowed from the local library.   
  
Kara insisted that Winn get Mon-El a library card, since Kara decided that the Internet should not be Mon-El’s sole source of information. Mon-El isn’t sure why Kara thinks that, since the Internet has been very informative so far.  
  
J’onn grunts at him, sitting on the faded grey couch and reading through some files. “I have a lot of things to get through for tomorrow.”   
  
“That’s all right.” Mon-El sits down next to him, leaving a few inches between them, and smiles. “I was thinking, since I don’t have a job or anything, I could go and travel a bit. Explore this wonderful new world I ended up on. I figured I’d start with Central and South America. Didn’t you live there for a bit?” he asks casually, flipping open the book to some beautiful pictures of the rainforest.   
  
“I did, yes,” J’onn replies, scooting away from Mon-El. “I don’t think you should leave the DEO for too long. You still have a lot to learn about life on Earth.”   
  
Mon-El beams at him, moving closer as he leafs through the book. “But how am I gonna learn if I’m staying here all the time, hmm? C’mon, just tell me about Peru.”   
  
With some reluctance, J’onn starts talking about the time he spent there and in other countries in South America, and once J’onn gets going, his enthusiasm clearly grows.   
  
Mon-El smiles, wondering how many people have heard these stories, and his wanderlust is definitely growing as well. Even if his question was just a way to spend some time with J’onn, his wish to travel is real, and he does want explore Earth beyond the United States at some point.   
  
But J’onn also keeps moving away from him, inch by careful inch, and Mon-El keeps moving closer, nodding along and asking questions.   
  
J’onn is talking about the Nazca lines, and Mon-el flips the book to a picture spread of the lines. Then he reaches for J’onn’s right wrist. “That condor, which one is -” he starts, but J’onn is already pulling his hand away. Mon-El, however, is stronger than Winn, and he holds on.   
  
“Let go of me!” J’onn snarls, pulling harder, and Mon-El lets go. “Don’t touch me.” He folds both arms across his chest, hands folded underneath them, but Mon-El got a glimpse of J’onn’s hands, and his right one had turned green.   
  
Mon-El tilts his head. “Why?” He closes the book. “Why can’t people touch you?”   
  
He watches J’onn’s face closely. J’onn definitely looks annoyed, but there’s something else underneath the anger. Mon-El is surprised to realise that it’s fear. “What are you afraid of?”   
  
J’onn stands up. “Leave now.”   
  
“Something’s wrong,” Mon-El says, standing up as well. “With you. And you’re not telling anyone. Why?”   
  
J’onn narrows his eyes at Mon-El. “It’s none of your business.”   
  
“Then whose is it?” Mon-El asks. “Have you told anyone you’re suffering from side-effects after the anti-White Martian treatment?”   
  
J’onn actually laughs at that. “Is that what you think is wrong with me?” He shakes his head, letting out another amused huff. “It has nothing to do with that.”   
  
“Then what is going on?” Mon-El asks, a little annoyed and worried. “Because something’s going on, and I don’t think you’ve told anyone.”   
  
J’onn looks at him for a long time, then shakes his head again. “It is nothing that you can help with. Now leave.” He walks away from Mon-El.   
  
“So something is wrong,” Mon-El says.   
  
J’onn pointedly doesn’t reply, instead pretending to be busy reading the files he’d been going through earlier.   
  
“I’m gonna find out what it is,” Mon-El tells him, picking up the book, “and then I’m gonna help you, whether you want me to or not.”   
  
J’onn looks at him when he says that, and for a moment he looks almost intrigued before his expression settles into his usual stoic mask. “Wanting has very little to do with it, Mon-El.”   
  
Mon-El waits for him to say more, and when it’s clear J’onn considers the conversation to be over, Mon-El leaves for his own quarters.   
  
He is definitely gonna help J’onn with whatever his issues are.

*

True to his word, Mon-El keeps an eye on J’onn and J’onn keeps ignoring Mon-El’s questions about his health, even as things get worse.   
  
J’onn isn’t just starting to avoid being touched, he’s starting to avoid other people all-together, keeping meetings as short as possible and excusing himself when more than a handful of people are around.  
  
“It’ll pass,” J’onn tells him a few evenings later when Mon-El asks him about it again. J’onn looks tired and keeps his hands firmly in his pockets. “Another week or so, at the most. I appreciate your concern,” he adds, in a tone that makes it clear he wishes Mon-El would leave him alone, “but I’ll be fine.”   
  
The next day, J’onn is talking to Alex and Mon-El about the possibility of letting Mon-El join Alex on a little recon mission outside of National City for the afternoon, when suddenly J’onn flinches, grits his teeth and clutches his head. He hisses in pain, and jumps back when Alex reaches for him.   
  
He shifts into his Green Martian form, something that always makes Mon-El take a step back, and J’onn groans as he rubs the ridges alongside his head.   
  
“J’onn, what’s wrong?” Alex asks, stepping closer. She reaches out with one hand, but keeps it a few inches away from J’onn’s arm. She looks at Mon-El. “You don’t seem to be affected.”  
  
Mon-El shakes his head. “I don’t think it’s Cadmus,” he says, because of course Alex’ first thought is an attack against aliens. “I think it’s whatever has been bothering him all week.”   
  
“J’onn, talk to me,” Alex says, patting him on the arm once to get his attention and wincing when J’onn flinches in pain. “J’onn, we can’t help you if you won’t tell us what’s wrong.”   
  
J’onn slides down onto the floor, still clutching his head. “Leave,” he grunts. “Just leave. Give me time.”   
  
Alex exchanges a look with Mon-El. “Stay here, I’m calling my mom.”   
  
Mon-El dutifully stays. “I can get you some water,” he offers. That’s what sick humans do for one another, he’s learned that from one of the many documentaries on humans Netflix offers.   
  
J’onn just groans again.  
  
*  
  
Eliza insists on multiple blood tests, drawing the blood herself while she tells J’onn off for not mentioning he wasn’t feeling well. “If this is because of the cure I created...”  
  
“It’s not that,” J’onn replies. He shifts back into Hank once Eliza has finished drawing his blood, but stays on the bed in the infirmary. “You don’t need to worry, none of you do.”   
  
Alex looks down at him. “You’ll have to excuse us for worrying about you anyway. Have you had headaches like that before?”   
  
“No,” J’onn admits, and he does look briefly worried. “Look, I’ve been through - I’ve been through this before.”   
  
“Is it a Green Martian thing?” Mon-El asks eagerly. “Is it contagious?”   
  
“What it is, is none of your business,” J’onn tells him, giving him a look that shuts Mon-El up for now.  
  
Eliza is less impressed. “It is our business if it’s because of something we did,” she says. “Now, I have some tests to run.”  
  
“And I have work to do,” J’onn insists, getting out of bed. He sways on his feet for a moment, and Mon-El reaches out to steady him.   
  
J’onn leans back against the bed instead, shaking his head. “I’m fine.” He stands up again, and walks away.  
  
Alex sighs. “Can you keep an eye on him?”   
  
Mon-El grins. “I was planning on that anyway!”   
  
*  
  
Eliza discusses the test results with Alex and J’onn, out of earshot of other DEO employees, and Mon-El nods along with the various biomedical terms Eliza uses.   
  
“I’ll admit that I’m not fully familiar with Green Martian physiology.” Eliza gives J’onn a sympathetic look. “But these values indicate that you are dying.”   
  
J’onn doesn’t look completely surprised. “I can see how it would give that impression, but believe me, I’m not.” He gestures at the print-out of the results. “Those levels will go back down again soon enough.”   
  
“I’d like to monitor the situation regardless.” Eliza smiles at him. “If anything, it’ll teach us more about Green Martians, and that’s always useful.”  
  
*  
  
The next day, things have gotten worse. J’onn is constantly shifting into his Green Martian form, running a fever when he is in his Hank Henshaw form, and still insists he’ll be fine.  
  
Alex and Eliza are in the laboratory, checking a few things, and Mon-El pulls a chair closer to J’onn’s bed.   
  
“So,” he says, sitting back and putting his feet on the bed. “Wanna tell me what’s up?”   
  
J’onn grits his teeth; he currently looks like Hank, beads of sweat on his forehead. “I am supposed to be fine!”   
  
“Well, you’re not.” It’s not that Mon-El isn’t worried, but by now he’s curious more than anything else. Whatever is going on, it even has J’onn himself confused. “But let’s review the facts. One, this is a Green Martian thing,” he says, gesturing at J’onn. “Two, it’s something you’ve been through before, so it’s a normal Green Martian thing. Three, it’s clearly worse than it’s ever been before. Four, you keep saying that it should be over soon, indicating that it’s something cyclical. Logical conclusion, it’s part of the Green Martian reproductive cycle.”   
  
J’onn stares at him. “How did you -” He closes his mouth when Mon-El throws his arms in the air and cheers.  
  
“I knew it!” he shouts, grinning when he folds his arms across his chest again. “It was either that, or you were gearing up for your next lifecycle and about to make yourself a cocoon or something.”   
  
J’onn sighs. “A cocoon would be better than this,” he grumbles.   
  
Mon-El is still grinning. “So I’m right. You’re in...what do you call it?”   
  
“The closest in English is ‘heat’,” J’onn says, looking like he’d rather by anywhere else than here. “I’ve been through one on Earth several times before, but they aren’t usually this bad.”   
  
“Maybe the difference is that you’re around more people,” Mon-El theorises. “I mean, you’ve spent a lot of time isolating yourself.”   
  
“Perhaps,” J’onn says. “But I can’t leave the DEO to find out. It’s too dangerous with Cadmus around.”   
  
“It’s even more dangerous if you aren’t feeling well,” Mon-El tells him. “Maybe you should go away for only a day, see if it helps.”   
  
“I did consider -” J’onn promptly closes his mouth when Alex and Eliza return.  
  
“I’m afraid things are only getting worse,” the older woman says. “J’onn, please, whatever is going on, tell me. We can fix it.”   
  
J’onn opens his mouth to speak, groans, then shifts into his Green Martian form. He sighs. “You can’t fix this, Eliza.”   
  
“Please, if you just let us try to -” Alex moves closer, and is cut off when J’onn shoves her away, hard. “J’onn!”   
  
J’onn shakes his head, shifting into Hank again. “I’m sorry, this isn’t - you should leave.”   
  
“I’ll stay with him,” Mon-El offers, earning him a glare from J’onn.   
  
“You better,” Alex tells him, and walks off with her mom.   
  
“You should leave too,” J’onn tells him, wiping the sweat off his forehead. “The urges are easier to control in this form, but it’s also becoming harder to stay in this form.”   
  
“The violent urges or the sexual urges?” Mon-El asks.  
  
J’onn glares at him, which Mon-El supposes is all the answer he’s gonna get.   
  
“I’ll get you some more water,” he says, and gets up to get some.

J’onn is quiet as he drinks, and Mon-El sits by his side, waiting for him to speak.  
  
During his one afternoon at Catco, James told him that sometimes, all you need to do in order to get people to tell you something, is be quiet yourself and let them fill the awkward silence instead.  
  
Mon-El watches the seconds tick by, biting his lip to keep quiet.  
  
After a minute, J’onn has closed his eyes and is resting.  
  
“How does a Green Martian heat work?” he asks. “How long does it last? How many have you had before? Is it just sexual arousal or also an urge to build a nest? Do the women get it too? Do you even have male and female Green Martians or is it one gender? Or more than two? Why didn’t you -”  
  
“Quiet.” J’onn opens his red eyes and glares at Mon-El.  
  
Mon-El promptly shuts up.  
  
“You are far too curious,” J’onn grumbles.  
  
“I am taking an interest in the health of my colleagues,” Mon-El replies. “Kara says that’s important.” He gives J’onn a sunny smile, and J’onn scowls back. “Look, I’m the only one here who knows you’re in heat. How can I help you fix it? Is there medication you can take?”   
  
J’onn sighs. “No, there isn’t. At least, not on this planet.” He glances at Mon-El, his anger fading. “My heat usually lasts a month and happens every two decades here on Earth. I’m halfway through.” He shrugs.   
  
“And it’s only getting worse,” Mon-El says, gesturing at him. “I mean, the shifting, the way you’re pushing people away... Is it true what Eliza said? About you dying?”   
  
He doesn’t think the DEO would run very well for very long with J’onn in charge. It doesn’t bear thinking about.  
  
J’onn is quiet for a moment. “It does feel worse than the previous times, and I have heard about Green Martians who died during a heat. It happens when their...needs aren’t met for various heats.” He looks away from Mon-El for a moment. “I didn’t think it would happen this fast.”   
  
“I’m guessing that was mostly a problem for Green Martians who travelled around the universe?” Mon-El asks. He supposes that makes sense, in a way. If you’re on a planet and you can’t procreate with any of the local species, why stay alive?   
  
“Yes, or those who were in prison for a very long time,” J’onn explains. “It’s considered an additional punishment.”  
  
Mon-El can imagine that. “And those...needs you mentioned, have you tried it with a human?”   
  
“No,” J’onn immediately replies. “No, our species are not compatible. The force involved, the secretions...” He shakes his head. “A human would die after mating with a Green Martian.”  
  
Mon-El knows he shouldn’t be intrigued, but he can’t help it. “Secretions?”   
  
J’onn narrows his eyes at Mon-El again. “I assume your parents told you how mating works?”   
  
“Not when there’s Green Martians involved,” Mon-El replies, grinning. “For all I know you’re one of those species who eats their partner after sex.” He can see the corner of J’onn’s mouth twitch in amusement.  
  
“We are not.”   
  
Mon-El leans back. “Okay, so, you need to mate in order to stop the heat, and there is a good chance that Eliza is right and you’re dying.”   
  
“It’s a possible outcome, yes,” J’onn tells him. “But I will be fine. I will leave the DEO for the remainder and isolate myself from others. It’s the least worst option we have.”   
  
“But what if you die?” Mon-El argues. “You can’t go and die in some cave in Peru. So what if you can’t mate with a human? What about - what about Daxamites?”

The words are out before he can take another second to think his offer through. While J’onn stares at him with surprise, Mon-El considers it.  
  
J’onn isn’t unattractive, not as Hank and not in his current form. J’onn doesn’t think much of Mon-El, but then Mon-El hasn’t given J’onn much cause to change his opinion.   
  
They need J’onn around, and Mon-El is willing to take one for the team.  
  
And all right, he’s very curious about what it would be like to be mated by a Green Martian. J’onn mentioned there was force involved, but Mon-El is pretty sure he’s strong enough to take what J’onn wants to give him.  
  
His eyes wander down to J’onn’s groin, covered by his usual armour. He can’t imagine what J’onn penis must be like, assuming he even has a penis. Would that be green too?   
  
“You don’t know what you’re offering.”  
  
“I’m offering to let you mate with me,” Mon-El replies. “Why? Does that mean that we have to bond as more permanent partners? Is it like marriage?”   
  
J’onn shakes his head. “No, it is common enough to mate for the duration of the heat alone. Mon-El, you cannot be serious. I told you, a human would die.”  
  
“And I’m not human,” he replies, smiling again. “C’mon, or am I that unappealing? I haven’t had any complaints yet.” He doesn’t get why J’onn is being so difficult over this. They can at least try.

“I am your superior at the DEO, it would be inappropriate -”  
  
“It would be inappropriate for me to let you die,” Mon-El snaps. “You’re not forcing me, J’onn. I want to help. I don’t know how to help half the time, and the other half of the time you don’t need my help, but right now, I know what needs to be done and what other options do you have? I mean, I could go around and look for another species that you could safely mate, if you can name me some, but it could take days to track ‘em down.”   
  
J’onn sighs. “You don’t know what you are agreeing to.”   
  
“Then tell me,” Mon-El insists, leaning forward. “Tell me what it’d be like to mate with you.”  
  
J’onn inhales sharply, and shudders. “Careful.”   
  
Mon-El frowns. “Why - ooh. Oh, is talking about it making it worse?” He glances at J’onn’s crotch, but there’s no bump. Well, the armour would cover that up.  
  
“Talking about it means thinking about it,” J’onn replies, folding his arms across his chest. “And thinking about it makes it worse, which is the last thing I need.”  
  
Mon-El gets up. He’s made his offer, and J’onn should take some time to think it over without him there to distract J’onn again. “I’m serious,” he says, looking down at J’onn. “If you say that it’s not a permanent thing, I’m willing to try. You guys studied me thoroughly when I got here, go through the files to see if it would kill me like it would with humans.”  
  
“You are braver than I thought,” J’onn tells him.   
  
He smiles. “Take that into consideration, please. The DEO needs you, alive and well.” He moves his arm, intending to pat J’onn reassuringly on the shoulder, then reconsiders and folds his hands behind his back. “You know where my quarters are, J’onn. Maybe I’ll see you later tonight.”   
  
He walks away, and J’onn doesn’t say anything.  
  
Mon-El isn’t sure if his stomach is squirming with worry over what the hell he got himself into now, or gleeful anticipation.

*

Mon-El wakes up with a start and sits up in bed. He blinks and realises that J’onn is standing in the doorway, the light coming in from the hallway framing his Green Martian form.  
  
Mon-El turns on the bedside lamp. “The middle of the night, J’onn? You couldn’t have done this earlier?” He yawns as J’onn walks over to the bed. It’s weird to see him without the armour and wearing a pair of dark sweatpants, and his torso doesn’t look that different from a human male’s, but it’s a little weird that there’s no nipples and his bellybutton is further to the side instead of in the middle.   
  
J’onn grunts and looks down at Mon-El. He grabs the bedcover and pulls it out of the way, dropping it on the floor.   
  
“Hey!” Mon-El reaches for the bedcover, but he’s too late. He glares up at J’onn, who is watching him with some surprise. “What? I always sleep naked.”   
  
“You’re still sure?” J’onn asks, his voice a little raspy.  
  
“About the mating? Yeah,” Mon-El replies, nervous anticipation making his stomach squirm again. “So, how exactly do you - oh. Huh.”   
  
J’onn lowers his sweatpants, letting them drop on the floor before stepping out of them. His groin is smooth and featureless except for a thin slit running down, and is a darker shade of green than the rest of his body. He follows Mon-El’s surprised gaze, and looks down at his own groin.   
  
Before Mon-El can ask how they’re supposed to mate if Green Martians don’t have any genitalia, he watches as the muscles of J’onn’s abdomen tense, and then the slit opens to reveal a penis, and two testicles emerge as well. “That’s...convenient,” Mon-El says, thinking of all the times he’d been kneed in the groin, either by accident or on purpose. Damn, having protective skinfolds would’ve made his life a lot less painful.   
  
J’onn’s penis is the same dark green as the rest of his groin, and the tip is about as thin as Mon-El’s index finger, while at the base it’s easily as thick as his wrist. Just below the head is where the ridges start, one ridge of small bumps running alongside the top, and two alongside the bottom. The bumps grow larger closer to the base, and Mon-El wonders what they’ll feel like inside of him.  
  
Oh God, J’onn is gonna fuck him any minute now.   
  
Mon-El gulps, and looks up at J’onn, who is still watching him quietly. His eyes are a dark red, and judging by the way J’onn is shifting on his feet, he’s very eager to get started. He’s clearly waiting for Mon-El to say he still wants to go through with this.  
  
“All right, let’s get started, then,” Mon-El says, trying not to sound nervous.  
  
J’onn immediately joins him on the bed, his large hands on Mon-El’s shoulders, pushing him down onto the mattress. He uses his knees to spread Mon-El’s thighs, then lowers his head to lick across Mon-El’s chest.  
  
Mon-El gasps at the sudden wetness, his own fingers digging into the sheets underneath him. He moves slightly to get more comfortable, and groans as J’onn pushes down more firmly. “I’m not trying to get away,” he grumbles.   
  
He is, however, acutely aware of how vulnerable his own position is, his legs forcibly spread by J’onn, and how J’onn’s green cock is hardening before his eyes. It grows thicker, curving slightly towards J’onn’s stomach, and the ridges seem to grow larger too.   
  
J’onn licks his chest again, and a warmth is starting to spread out across his skin, into his chest. It’s kinda nice, that warm glow inside of him.   
  
“How long is the mating gonna take?” Mon-El asks, enjoying the growing warmth.  
  
J’onn glances at him, his eyes a darker red now. “As long as I need.”   
  
Mon-El tells himself that it is totally not those words and that growly voice that’s making his own cock grow harder with interest, nope, not all.   
  
J’onn presses down on Mon-El’s shoulders again before taking his hands off him, then grabs him by the back of his knees, pushing them up and bringing Mon-El’s knees to his chest.   
  
Mon-El holds his breath, expecting to feel something against his ass any minute now, but instead of the thin tip of J’onn’s cock, J’onn lowers his head again and licks once, twice, three times across Mon-El’s hole in quick succession.  
  
Mon-El jerks back in surprise, which earns him an annoyed grunt from J’onn. “Give a guy a warning!” Mon-El says, and oh yes, the same warm tingle that he felt in his chest is now also blossoming down there. It really is very nice and relaxing.  
  
J’onn ignores him, shuffling forward until the tip of his cock is nudging Mon-El’s hole open, and then he keeps moving forward until the tip is inside.  
  
“All right,” Mon-El says, “all right, now take it slow and - fucking hell!”   
  
J’onn pushes in hard, bump after bump after bump sliding in and stretching Mon-El’s hole wider and wider. The pain is sharp and sudden, and Mon-El is gasping for air, flinching and trying to move away, but J’onn has a firm grasp on Mon-El’s hips.  
  
“Fucking hell,” Mon-El says again, once the worst of the pain is subsiding. He remembers what J’onn said about the force involved and how mating with a Green Martian would kill a human. Is this what he meant? The pain? The stretching?   
  
J’onn ignores Mon-El’s reaction, and begins to thrust. Every time one of the bumps is pushed in or out, Mon-El gasps in pain.   
  
It’s fine, he tells himself. It hurts, but not as badly as earlier, and his body will adjust, and he’s doing this to help J’onn. J’onn, who probably can’t help the way he’s fucking Mon-El right now.   
  
“It’s all right,” Mon-El mutters, as much to himself as to whatever part of J’onn is listening. “It’s all right.”   
  
The warm glow inside of him is still there, almost too hot to be good, but it takes the worst edge off the pain. He runs a hand across his chest, tracing the wet path from J’onn’s tongue. Is that part of the mating too? A way of claiming him?   
  
J’onn’s thrusts are speeding up, pushing in harder, and the bed is creaking underneath them.  
  
Mon-El whimpers. It’s still a little painful, but each thrust is easier to take than the last, and then J’onn slams in hard, his cock swelling up inside of him, so much that Mon-El is groaning with how full he feels, and then J’onn’s cock twitches as he comes.   
  
J’onn groans above him, throwing his head back and crying out. Mon-El wonders for a moment if he’s in pain.   
  
The warm glow centred in his ass is intensifying, and Mon-El feels hot and flushed all over. He needs fresh air, he needs some ice, he needs - he needs - he needs to be fucked.  
  
A strong wave of arousal courses through his body, making him moan. Yes, of course he needs to be fucked, what else could he possibly need?   
  
J’onn is above him, and Mon-El reaches out for him, running his hands over J’onn’s arms, towards his shoulders. “Please,” he mumbles.   
  
Instead, J’onn is pulling out, panting hard as he sits back. His hands are drifting away from Mon-El’s hips, running across the inside of his thighs before dropping onto the sheets.  
  
Mon-El whimpers at how empty and wrong he feels. No, he needs J’onn’s cock back inside of him, and he needs it now. “Please?” he asks, spreading his legs further. He can feel some of J’onn’s come drip out of him.   
  
His own cock is achingly hard, and Mon-El wraps one hand around it, tugging and moaning at how it’s nothing compared to being fucked by J’onn.   
  
Suddenly, J’onn’s hands are on him, on one of his knees and then on his shoulder, turning Mon-El until he’s on his stomach.  
  
Mon-El groans happily, rubbing his cock against the sheets underneath him, and then J’onn pulls him up until he’s on his knees. Mon-El is torn between disappointment that he’s got nothing to rub against his cock, and relief, because J’onn wouldn’t position him like this unless he was planning to fuck Mon-El again, right?   
  
Right?   
  
Mon-El rests his head against the pillow, and wriggles his ass. “Please!” he manages. It’s unbearable how empty he feels, what is J’onn waiting for?   
  
J’onn grabs Mon-El’s hips tight, and when Mon-El feels the tip of J’onn cock against his ass, he tries to push back immediately. He needs this.  
  
J’onn holds him in place, but does push in to the hilt, making Mon-El moan happily against the pillow.   
  
There’s nothing else but the bliss of J’onn’s cock thrusting in and out of him, of the ridges rubbing against his insides in a maddening way, and soon Mon-El’s cock is twitching as he comes all over the sheets. He’s biting into the pillow as he moans, pushing back for more more more of J’onn’s cock, and once the pleasure from his orgasm fades, there’s none of the sated afterglow that usually follows.  
  
Instead, all Mon-El feels is a stronger need and desire, a more powerful urge than before.

If J’onn notices that Mon-El has just come, he doesn’t show it. He keeps thrusting away, grunting occasionally.  
  
Mon-El doesn’t think about the lack of satisfied afterglow either, because all his thoughts are centred on J’onn’s ridged cock and how great it feels when the bumps go in and out of him.   
  
He lets out needy whimpers into the pillow underneath him, his fingers digging into the sheet. “Please, please.” He pushes back with his hips, rocking back in a counter-rhythm to J’onn.  
  
J’onn grunts, his grip on Mon-El’s hips tightening briefly before relaxing. Not too long after, his cock is swelling up inside Mon-El again.  
  
“Yes, please!” Mon-El moans, because he knows what this means. It means J’onn is enjoying himself, which means he’ll keep fucking Mon-El. He gasps when another load is shot inside of him, filling him even further.  
  
He shudders at the resulting heat growing inside of him, at the strong desire that accompanies it.   
  
J’onn begins to pull back, and Mon-El moves back as well. “No!” he cries out. “No, please, no, please, more, please, need!” He’s babbling, because the thought of not having J’onn’s cock inside of him is terrifying.   
  
J’onn pauses, then grunts, giving Mon-El a friendly slap on the ass. He moves forward again, one arm wrapping around Mon-El’s waist, and he slowly rolls them both to the side, until they’re spooning.  
  
Mon-El whimpers and sighs happily as J’onn’s rubs inside of him in new and interesting ways. He presses back against J’onn, against his tough skin and hard muscles.   
  
J’onn starts to fuck him again, his hand running up and down Mon-El’s side soothingly, before he moves it down and lifts up Mon-El’s thigh to give himself more space.   
  
Mon-El’s moaning, enjoying every thrust, and his orgasm hits him before he even realises it’s been building. Come spills out of his cock, but there’s still no nice, satisfied feeling.   
  
He still wants more.   
  
He doesn’t even care that he’s just come, too busy pushing back and shifting so he can be fucked deeper. “Please, please, more,” he mutters, not sure what ‘more’ is. It’s not like there are more Green Martians who could fuck him.  
  
Mon-El whimpers at that thought, at the thought of another Green Martian joining them and fucking him as well. Maybe this second Green Martian could use his mouth, since Mon-El is sure J’onn’s cock would taste as good as it feels.   
  
The thought is gone before he can focus on the practicalities. It’s a struggle to focus, the only thoughts running through his mind are how good it feels to be fucked, how good J’onn’s cock feels inside of him, and how nice it is to lie here and not have to do anything but enjoy himself. No worries, no concerns, only bliss.  
  
He feels like he’s floating, warm and happy, and then he’s gasping as J’onn’s cock is swelling up again, filling him up further and there’s another wave of need and desire and more coursing through him.   
  
As J’onn keeps fucking him, Mon-El finds that the sheets underneath him are scratchy, that the way J’onn is holding him is too tight, that J’onn’s chest brushing against his back is too much.   
  
There’s too much, and not enough, and Mon-El is coming again, and it almost hurts at how overwhelming the sensation is.  
  
He doesn’t beg J’onn to stop. He doesn’t want J’onn to stop. Because not being fucked would be even worse than this, and it does feel good. Mostly.   
  
Mon-El isn’t sure how long it lasts. He barely even notices when he comes, but is vaguely surprised when he sees his cock twitching without any come coming out.   
  
He notices every orgasm J’onn has. It’s difficult not to. The way the ridges swell up, the way the thrusts speed up and J’onn’s breath comes faster, hot huffs against the back of Mon-El’s neck, and then J’onn’s fingers dig into Mon-El’s thighs and J’onn thrusts in deep.  
  
It’s better than coming himself, Mon-El thinks dreamily as heat and warmth overtake him. But that feeling fades, replaced by a stronger need, and a more sensitive skin. Even the sheets that were so soft only a few hours - was it hours? - ago are like sandpaper now, and there’s nothing he can do.  
  
Mon-El keeps his eyes closed, moaning and whimpering and barely able to hang on. He can do this, he can handle it. He’s supposed to handle it. It’s - it’s important that he makes it through this, even though he’s not entirely sure why anymore.   
  
All he can do is relax as much as possible, and endure.  
  
*  
  
He must’ve fallen asleep at some point, because Mon-El wakes up, disoriented and sore all over.  
  
He’s still lying on his side, and rolls onto his back. A split-second later he’s crying out at the sudden flare of pain from his ass.  
  
He rolls onto his stomach, whimpering at the way the sheets rub against his cock.   
  
Okay, side it is.  
  
Now that he’s as comfortable as possible, Mon-El tries to gather his thoughts. He remembers J’onn coming in, and then the initial pain, and then how _incredibly_ good it felt, and then... then more pain, but somehow it was good as well.   
  
The door to his room opens and it’s J’onn looking like J’onn - or at least, looking like Hank, dressed in his DEO uniform.   
  
Mon-El doesn’t move, because why bother pulling the covers up?   
  
J’onn hesitates in the doorway, then nods to himself and walks in, closing the door. “So, you’re awake.”   
  
“Barely,” Mon-El mutters. “Did you fuck me or drop me from a building?”   
  
J’onn walks closer, stopping by the side of the bed. “And you’re still yourself,” he remarks, smiling just a little. “Good.”   
  
Mon-El glares at him. “You seem like you’re back to normal. Are you?”   
  
J’onn nods. “Yes, the heat has passed, thanks to you. I must say, I am... impressed.”   
  
“Impressed?” Mon-El asks, pushing himself up on one elbow. “Impressed? All I did was let you fuck me. I just laid here. I’m pretty sure you did all the work.” It is good to know it was worth it, though. For J’onn’s sake.   
  
“You endured a Green Martian in heat,” J’onn says, his tone grave and serious, as if Mon-El has just defeated Cadmus singlehandedly. “I did mention the force and secretions involved.”   
  
“You mean how whenever you came, I’d feel even loopier?” Mon-El asks. Because most of the night is a blur, but he can recall some of the feelings, like dim echoes.   
  
“The aphrodisiac properties are overwhelming, and is what makes mating with a human impossible,” J’onn explains. “It would have a permanent effect on them. After I reviewed your file, I realised - or at least I hoped - that your metabolism would be high enough to break down the aphrodisiac before it had a chance to do that to you.”  
  
Mon-El is struggling to take it all in, and he wishes J’onn had given him this entire explanation _before_ fucking him through the mattress. “You mean, a human would permanently feel all...” He gestures vaguely, and gulps. No wonder J’onn hadn’t wanted to fuck a human.  
  
“Yes. Or at least, for as long as it takes the secretions to take over completely, destroying the brain neuron by neuron, until -”  
  
“I got the idea!” Mon-El holds up his hand. Okay, now he gets why J’onn didn’t tell him beforehand. If he had known J’onn’s come might literally eat his brains, he’s not sure if he would’ve agreed. “Hang on, you said you weren’t sure if my metabolism was high enough!”   
  
“True,” J’onn says, and his expression is one of deep regret. “I will admit, had I been more in control of myself, I would have never given in. With the information we have about alien species, I could’ve found someone more suitable. Safer. Eventually.” J’onn leaves the ‘maybe’ unsaid.   
  
“But I was right here, and I offered,” Mon-El replied. He doesn’t blame J’onn, how can he? Even if it killed him, well, who does the DEO need more, someone who can make a difference or someone who is in the way? Mon-El lies back down. “Don’t tell Kara.”  
  
J’onn stares at him. “You think I _want_ to tell anyone?”  
  
“Well, it would be good to record it somewhere. So everyone’s warned for your next heat. I might not be around for that,” Mon-El tells him. Who knows where he’ll be by then.   
  
J’onn smiles now, a proper, real smile. “You are braver than you think, Mon-El. And stronger. There is a place here for you at the DEO, and I am sure that in time you will make a fine agent.”   
  
Mon-El stares at him, torn between wanting to explain that no, he didn’t meant that he might not be around for J’onn’s next heat because he might be dead, and just wanting to bask in J’onn’s approval and accept the compliment. “Thanks,” he says, smiling back. “You can tell Kara that bit. And Alex. And Winn. And Eliza. And James. Oh, and that cute guy I saw in the cafeteria on Tuesday. Blond hair, curls. Does he work here?”   
  
J’onn shakes his head. “Mon-El, get some sleep.” He pulls the bedcovers up, giving Mon-El a friendly pat on the shoulder. “You clearly need it. I don’t think all the aphrodisiac is out of your system yet.”  
  
“I feel fine,” Mon-El complains. “Honestly, I don’t -” He catches J’onn’s smirk. “Was that - was that a _joke_ , J’onn? Did you make a joke at me?” He laughs. “Well, I’ll have to stay at the DEO now that it turns out you do have a sense of humour.”


End file.
